With a fast development of communication technology, more and more user equipments are accessed to a wireless network. The user equipments need to transmit signals to a network side device, to implement the communication. In a signal transmission process, there is a difference between a preset transmission time period and an actual transmission time period during which the signal is transmitted from the user equipment to the network side device, and thereby resulting in that the signal is not received by the network side device at a preset time slot. In this case, the time slot for receiving the signal by the network side device is the same as that for receiving a signal by the network side device from other user equipments. Thus, different signals produce mutual interference. In order to address this issue, the user equipment may send a signal in advance, and a length of time for advancing a transmission of the signal is defined as a TA (Timing Advance). However, a position of the user equipment may change at any time instant, a time instant when the signal sent by the user equipment arrives at the network side device changes accordingly, hence the TA needs to be adjusted by the user equipment continuously.
In the conventional technology, the TA is adjusted as follows. In an LTE (Long Term Evolution, long term evolution) system, a UE (User Equipment, user equipment) completes initial downlink synchronization with a network side device eNB (evolved Node B), and then adjusts the TA by an RA (Random Access) process. The process for adjusting the TA includes that: the UE sends a random access preamble sequence to the eNB on a specified time-frequency resource; the eNB receives the random access preamble sequence and sends to the UE a random access response message including a TA command; and the UE receives the random access response message and adjusts the TA. In the signal transmission process between the UE and the eNB, the UE needs to adjust the TA continuously, to ensure that a time instant when the signal sent by the UE arrives at the eNB aligns with a time slot for the eNB.
In a process for implementing the present application, the inventor found at least the following issues in the conventional technology.
Time-frequency resources used for the LTE system is acquired by purchasing a license, and the time-frequency resources are used exclusively. Thus, in the LTE system, different UEs may use respective time-frequency resources to adjust the TA according to the preset system configuration. However, for free frequency bands, the time-frequency resource is obtained by competition due to the limitation that a device generates harmful interference in the regulations set by the spectrum management mechanism. Thus, particular time-frequency resources can not be distributed to a certain user equipment, and thereby leading to that the user equipment can not use the method for adjusting the TA in the LTE system in the case of no certain time-frequency resource. Therefore, an application range of the method for adjusting the TA in the LTE system is limited, and the method for adjusting the TA in the LTE system can not be applied to a wider field to reduce interference between signals.